Stop detector



Dec. 18, 1934. A. E HUDD 1,984,679

STOP /DETECTOR Filed May 2, 1928 2 Sh-et-ZJLS--Slle-el l f l a Q w e JIl Il l l D "Y i 5% fra HZFPeiEJ-Iucli Patented Dec. 18, 1934 UNITEDSTATES tatie STOP DETECTOR Alfred E. Budd, Evanston, Illy., assigner, bymesne assignments, to Associated Electric Laboratories,'Inc., Chicago,Ill., a corporation of Dela- Ware Application May 2, 1928, Serial No.274,412

13 Claims.

The present invention relates in general to stop detectors, but isparticularly concerned with the constructiony and design of a pneumaticstop detector of the general type disclosed in the copending Huddapplication, Serial No. 170,048,

filed February 21, 1927.

The objects of the present invention are to provide devices of theforegoing character which are very reliable, economical in the use ofcompressed air, readily accessible for replacement or repair of parts`and of very rugged construction. Referring now to the drawings, Fig. 1is a plan View in cross section, taken on lines X-Y of Fig. 2; Fig. 2 isan end view in elevation as seen when looking'in the direction indicatedby arrow A of Fig. 1; while Fig. 3 is a perspective of 'a detail notsuiliciently disclosed in Figs. 1 or 2. The` stop detector consists of aflanged cylinder 7, into which is inserted a piston 22. This piston 22has within it a detector piston 24. Within this detector piston isrotatably secured, by pin 3, a valve actuator 21. Segments of thedetector piston 24 are cut away asshown in Figs. 1 and 3, and actuatorsprings 30 are secured thereto to hold the valve actuator in properalignment. The piston 24 is held within the piston 22 by a stop andguard plate 4 secured to the piston 22 by 'agnumber of` machine screws5. By reference to Fig.3 it'will be seen that a limited portion of Vthepiston'24 is also cut away to form shoulders 24', which will encounterthe stop and guard plate 4 and definitely limit the youtward move- -mentof the piston. The piston 24 is held iirmly against this guard' plate bya compression spring 25, within the piston 22 and pressing against theleft end of the piston 24.

A valve stem 23 extends into the left portion of the detector piston 24and out through the left portion of the piston 22. rlhis stem isprovided with a leather washer 10 for engaging a raised portion 35 ofthe piston 22 when the piston 22 moves to the right as will subsequentlybe described. At the left end of the stem 23 is also secured a valve 13.1n a solid portion oi the wall of piston 22 an air duct 26 extends, froma fluted portion 11 of the stem 23, to the wall of the cylinder "7.vThis portion of the wall of the cylinder is solidhowever and thereforethe opening 26 is normally blanketed. Onto the left end of the piston 22is secured a piston head 15, which has perforations *14 for admittingair to the` valve 13.

The piston head 15 has a threaded portion for receiving a guide bolt 17.Upon this guide bolt is placeda stop plate 8, having a square opening Acompression spring 29 surrounds the bolt 17 and is held in placeslightly compressed, by steel washer 2 and nut 18. This latter part ofthe assembly is completely covered over, andv with the stop plate 8, isheld in place by a number .5 of machine screws 9.

The operation of the device, which will enable a better understanding ofthe invention, will now be given. For this purpose it will be assumedthat, through the medium of holes in the flanges of the cylinder 7, itis irmly secured in a denite fixed relation to the periphery 40 of arotatable element. It will further be assumed that a pneumaticallyoperable device is connected with the exhaust opening 28 and that asource of air pres- I sure is available for application to the intakeopening 6 to supply air to the stop detector assembly at will. i

It will rst be assumed that when air is lsupplied to the opening 6 theelement40 is stationary. 20 Under this condition the air suppliedthrough opening 6 builds up in the air` chamber 20, passes through ports27 in stop plate 8 and against the piston head 15. It will be noted thatthe' ports 14 are open permanently, but'little or `no airy passes beyondvalve `13 because, if it is open at the time air is applied toit, it isinstantly closed by the air pressureV and this pressure simply assistsin keeping the valve 13 on its seat.

As the pressure builds up piston 22, carrying piston 24 with it, movesforward until the valve actuator 21 encounters the rotatable element 40.When the valve actuator 21 encounters the rotatable element (assumed tobe stationary at this time), further movement of the detector piston 24is prevented. However, the piston 22 continues to move forward and as itdoes so valve stem 23 encounters and is stopped by the valve actuator21. As the piston 22 continues its movement valve 13 remains stationary,but its associated seat,

f being a part of the piston 22, continues to move forward until theport 26 is in alignment with the opening 28. Air pressure applied to theinput opening 6 may now freely pass to the exhaust opening 28 via valve23 and port 26, to bring about the operation of any pneumatic apparatuswhich may be connected therewith.

It will be noted that shortly following the opening of valve 13 theraised portion 35 of the piston 22 encounters the leather washer 1Y0.This prevents further forward movement of the piston and prevents awaste of air past the stem 23 at this point.

Upon release of piston 22 air may be exhausted from the passage 28either by a normally open passage through piston 22, not shown, or byany well known manual valve external to the arrangement shown.

We will now assume that at the time air is supplied to the inlet opening6 that the element 40 is rotating. Under this condition, as soon as thevalve actuator 21 rencounters the :element '40 the valve actuator isdeflected out of range of the stem 23. Since the valve actuator 21 isnot encountered by the stem 23 the stem continues movement with thepiston and not being raised, valve 13 will not open and althoughthe-port -26 may come into alignment with the port 28noair can escapeowing to the closed condition of valve 13. Consequently the pneumaticdev-iceconnected with the opening 28 cannot receive air pressure for itsoperation.

The stop detector is restored by removing the air pressure from theinlet opening 6. When this occurs spring 29, compressed during theforward movement ofthe piston '22, restores the piston to itsinit'ialposition, while the spring 25, also compressed during Athe .forward.movement of 'the piston 22 and after the piston 24 ceased movement,Yrestores the piston 24 to its initial position with respect to thepiston 22. Of course,.in cases where `the -valve actuator .21 has beentilted, owing to ."i-tszhaving encountered a moving element, springs `30function also, rto restore it to its normal posif tion..

.Fnomthe foregoing it will beuappreciated-that `:applicant has .inventeda much needed device :of the fchara'cterdescribed, which can be dependedyuponto accomplish the results intended.

'What isiclaimed is:

1. In a valve structure, a cylinder, a piston `in saidcyl-inder, asecond piston within the first, :a valve having an operating stem withinsaid pis- -ftonsfa valveactua-tor, Vsaid pistons being 4operablefte-.cause:saidvalveactuatorto be encountered by said lstem to actuatesaid valve. f .2. In 'avalve structure, vva cylinder, a piston in saidcylinder, a second `piston within the iirst, a

valvehaving an voperating rstem within `said pistons, :a valve actuator,said pistons being operable toi-cause said valveactuator to beencountered by -sai-d stem to actuate `said valve, and zmeans -forpreventing the movement of said pistons from causing the `actuation ofsaid valve to occurin certain instances.

f 3. In la valvestructure, an air input port and 'an-exhaustgport, aplurality of restrictions in 4an .air rpath between said fportscomprising poppet f ya cylinder and air chamber, a piston within saidcylinder, meansin said 'air chamber for restoring said `piston`following its operation, a second piston carried within the first, andmeans. for at `times causing one of` said pistons to move relative tothe other responsive to the `application vof air to .said air chamber.

.6. Incombination with a movable element, a

valve, valve operating means cooperating with said element, means forsupplying fluid pressure to said means, means responsive to theapplication of fluid pressure for operating said valve to cause theescape of iiuid therethrough only if the movable element is stationary.

y7. I-n a-mechanism for rdetectingwhether a device is in motionforstationary, :a member, means for applying pressure to said member tomove it Ainsa normal direction towards the surface of such device, andmeans in said mechanism carried by said member operated responsive tosuch movement `only in case such device is stationary.

8. Ina mechanism for detecting whether a device isin motion-orstationary, a pneumatically operable piston, .a valve and valve actuatorcarried by said piston, `and movable means engaged Ab'y'sai'dactuatortolcause or prevent further movementfof said piston from causing theactuator to actuate said valve dependent on the state of said movablemeans.

9. Inavalve, apn'eumatically operablev element, an air releasemembertassociated with; .saidelement. an actuator for said air release`vmember,

and means eiiective upon .movement of said element for either causingsaidactuator'tofoperate or prevent' it from operating saidfair releasemember., depending on the condition of said means.

10. .In a mechanism, almovable element, a secondmovable elementassociated .with the iflrst, an actuator #for said second Amovableelement, and .means effective upon movement of said first element foreitherpreventing said Aactin-ttor 'from operating said second element orcausing it to `operate the element, depending on the condition of Vsaidmeans.

11. A resetting device comprising va casing,

.means slidable inthe casing includinga slidable tstem, atrip 'member`pivoted to .said stem and adapted tobedrawninto said casing toalinewith the stemand to be projectedinto contact with .a relatively/movablepart for 'swinging said Atrip member, 'and' resetting effecting .meansoperable when said .stem is moved to bring said tripmember against said-part without said mp .memberA being swung. i

12. A resetting device comprising a cylinder,

i a piston slidable in Asaid cylinder, a secondfpiston slidable `in theiirst-named. piston and .having a.

stemsadapted to be projected from the cylinder, a.

trip member pivoted to saidstem to be `mnved into contact with.arelatively movable part, and resetting effecting means operablewhensaid pistons are moved and the second piston is limited in itsmovement by the contact of the trip member f with said part without saidtrip member being swung relatively to said stem.

13. A resetting device for automatic train control Vcomprising vehiclecarried means including a member mounted for sidewise movement andendwise movement into and out of engagement with a movable part, meansfor projecting the member into engagement with the part, said membermovable sidewise when engaging said part While the vehicle is moving,and having no i55 sidewise movement when the part is engaged while thevehicle is stationary, and. means for supplying fluid pressure to aresetting device only when the vehicle is stationary.

